Clonal Selection
Definition
The process by which an antigen binds selectively to the lymphocyte (B or T cell) that carries the complementary surface receptor, triggering proliferation of that cell into a clone of identical specificities. It explains both the precision and the memory of adaptive immunity.
- Trigger
- Antigen binding to a matching lymphocyte receptor
- Cell types
- B cells and T cells
- Result
- Proliferation into a clone of identical specificity
- Explains
- Immune precision and immunological memory
Common questions
How does clonal selection explain why a second exposure to a pathogen produces a faster immune response?+
The first exposure expands a clone of lymphocytes specific to that antigen and some become long-lived memory cells, so on re-exposure a much larger pool of matching cells is already present and can respond faster than the small starting pool available at first contact.
Why is clonal selection relevant to forensic serology or immunology testing?+
It underlies why antibody-based tests, such as those used to detect species-specific or blood-group antigens, work at all: the antibodies used in the assay were themselves produced by clonally selected, antigen-specific lymphocyte lineages, giving the test its specificity.
Related terms
- Affinity Maturation
- The progressive increase in antibody-antigen binding strength that occurs during the secondary and subsequent responses. It results from somatic hypermutation of immunoglobulin...
- Cytotoxic T Cell (CTL)
- A CD8+ T lymphocyte that recognises peptide antigens presented on MHC class I molecules and kills the target cell by releasing perforin...
- Helper T Cell
- A CD4+ T lymphocyte that recognises antigen on MHC class II molecules and secretes cytokines that amplify both the humoral and cellular...
- Memory B Cell
- A long-lived B cell generated during a primary immune response that retains the antigen-specific receptor and persists in lymphoid tissue. On re-exposure...
- Plasma Cell
- A terminally differentiated B cell that has lost most of its surface immunoglobulin and become a high-output antibody factory, secreting thousands of...